forked from OSchip/llvm-project
898 lines
39 KiB
C++
898 lines
39 KiB
C++
//===--- LoopConvertCheck.cpp - clang-tidy---------------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#include "LoopConvertCheck.h"
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#include "clang/AST/ASTContext.h"
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#include "clang/ASTMatchers/ASTMatchFinder.h"
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using namespace clang;
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using namespace clang::ast_matchers;
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using namespace llvm;
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namespace clang {
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namespace tidy {
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namespace modernize {
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static const char LoopNameArray[] = "forLoopArray";
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static const char LoopNameIterator[] = "forLoopIterator";
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static const char LoopNamePseudoArray[] = "forLoopPseudoArray";
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static const char ConditionBoundName[] = "conditionBound";
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static const char ConditionVarName[] = "conditionVar";
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static const char IncrementVarName[] = "incrementVar";
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static const char InitVarName[] = "initVar";
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static const char BeginCallName[] = "beginCall";
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static const char EndCallName[] = "endCall";
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static const char ConditionEndVarName[] = "conditionEndVar";
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static const char EndVarName[] = "endVar";
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static const char DerefByValueResultName[] = "derefByValueResult";
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static const char DerefByRefResultName[] = "derefByRefResult";
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// shared matchers
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static const TypeMatcher AnyType = anything();
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static const StatementMatcher IntegerComparisonMatcher =
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expr(ignoringParenImpCasts(
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declRefExpr(to(varDecl(hasType(isInteger())).bind(ConditionVarName)))));
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static const DeclarationMatcher InitToZeroMatcher =
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varDecl(hasInitializer(ignoringParenImpCasts(integerLiteral(equals(0)))))
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.bind(InitVarName);
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static const StatementMatcher IncrementVarMatcher =
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declRefExpr(to(varDecl(hasType(isInteger())).bind(IncrementVarName)));
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/// \brief The matcher for loops over arrays.
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///
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/// In this general example, assuming 'j' and 'k' are of integral type:
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/// \code
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/// for (int i = 0; j < 3 + 2; ++k) { ... }
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/// \endcode
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/// The following string identifiers are bound to these parts of the AST:
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/// ConditionVarName: 'j' (as a VarDecl)
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/// ConditionBoundName: '3 + 2' (as an Expr)
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/// InitVarName: 'i' (as a VarDecl)
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/// IncrementVarName: 'k' (as a VarDecl)
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/// LoopName: The entire for loop (as a ForStmt)
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///
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/// Client code will need to make sure that:
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/// - The three index variables identified by the matcher are the same
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/// VarDecl.
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/// - The index variable is only used as an array index.
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/// - All arrays indexed by the loop are the same.
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StatementMatcher makeArrayLoopMatcher() {
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StatementMatcher ArrayBoundMatcher =
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expr(hasType(isInteger())).bind(ConditionBoundName);
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return forStmt(
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unless(isInTemplateInstantiation()),
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hasLoopInit(declStmt(hasSingleDecl(InitToZeroMatcher))),
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hasCondition(anyOf(
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binaryOperator(hasOperatorName("<"),
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hasLHS(IntegerComparisonMatcher),
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hasRHS(ArrayBoundMatcher)),
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binaryOperator(hasOperatorName(">"), hasLHS(ArrayBoundMatcher),
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hasRHS(IntegerComparisonMatcher)))),
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hasIncrement(unaryOperator(hasOperatorName("++"),
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hasUnaryOperand(IncrementVarMatcher))))
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.bind(LoopNameArray);
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}
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/// \brief The matcher used for iterator-based for loops.
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///
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/// This matcher is more flexible than array-based loops. It will match
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/// catch loops of the following textual forms (regardless of whether the
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/// iterator type is actually a pointer type or a class type):
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///
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/// Assuming f, g, and h are of type containerType::iterator,
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/// \code
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/// for (containerType::iterator it = container.begin(),
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/// e = createIterator(); f != g; ++h) { ... }
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/// for (containerType::iterator it = container.begin();
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/// f != anotherContainer.end(); ++h) { ... }
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/// \endcode
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/// The following string identifiers are bound to the parts of the AST:
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/// InitVarName: 'it' (as a VarDecl)
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/// ConditionVarName: 'f' (as a VarDecl)
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/// LoopName: The entire for loop (as a ForStmt)
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/// In the first example only:
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/// EndVarName: 'e' (as a VarDecl)
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/// ConditionEndVarName: 'g' (as a VarDecl)
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/// In the second example only:
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/// EndCallName: 'container.end()' (as a CXXMemberCallExpr)
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///
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/// Client code will need to make sure that:
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/// - The iterator variables 'it', 'f', and 'h' are the same.
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/// - The two containers on which 'begin' and 'end' are called are the same.
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/// - If the end iterator variable 'g' is defined, it is the same as 'f'.
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StatementMatcher makeIteratorLoopMatcher() {
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StatementMatcher BeginCallMatcher =
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cxxMemberCallExpr(
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argumentCountIs(0),
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callee(cxxMethodDecl(anyOf(hasName("begin"), hasName("cbegin")))))
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.bind(BeginCallName);
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DeclarationMatcher InitDeclMatcher =
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varDecl(hasInitializer(anyOf(ignoringParenImpCasts(BeginCallMatcher),
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materializeTemporaryExpr(
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ignoringParenImpCasts(BeginCallMatcher)),
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hasDescendant(BeginCallMatcher))))
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.bind(InitVarName);
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DeclarationMatcher EndDeclMatcher =
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varDecl(hasInitializer(anything())).bind(EndVarName);
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StatementMatcher EndCallMatcher = cxxMemberCallExpr(
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argumentCountIs(0),
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callee(cxxMethodDecl(anyOf(hasName("end"), hasName("cend")))));
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StatementMatcher IteratorBoundMatcher =
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expr(anyOf(ignoringParenImpCasts(
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declRefExpr(to(varDecl().bind(ConditionEndVarName)))),
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ignoringParenImpCasts(expr(EndCallMatcher).bind(EndCallName)),
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materializeTemporaryExpr(ignoringParenImpCasts(
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expr(EndCallMatcher).bind(EndCallName)))));
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StatementMatcher IteratorComparisonMatcher = expr(
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ignoringParenImpCasts(declRefExpr(to(varDecl().bind(ConditionVarName)))));
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StatementMatcher OverloadedNEQMatcher =
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cxxOperatorCallExpr(hasOverloadedOperatorName("!="), argumentCountIs(2),
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hasArgument(0, IteratorComparisonMatcher),
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hasArgument(1, IteratorBoundMatcher));
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// This matcher tests that a declaration is a CXXRecordDecl that has an
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// overloaded operator*(). If the operator*() returns by value instead of by
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// reference then the return type is tagged with DerefByValueResultName.
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internal::Matcher<VarDecl> TestDerefReturnsByValue =
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hasType(cxxRecordDecl(hasMethod(allOf(
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hasOverloadedOperatorName("*"),
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anyOf(
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// Tag the return type if it's by value.
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returns(qualType(unless(hasCanonicalType(referenceType())))
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.bind(DerefByValueResultName)),
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returns(
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// Skip loops where the iterator's operator* returns an
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// rvalue reference. This is just weird.
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qualType(unless(hasCanonicalType(rValueReferenceType())))
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.bind(DerefByRefResultName)))))));
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return forStmt(
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unless(isInTemplateInstantiation()),
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hasLoopInit(anyOf(declStmt(declCountIs(2),
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containsDeclaration(0, InitDeclMatcher),
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containsDeclaration(1, EndDeclMatcher)),
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declStmt(hasSingleDecl(InitDeclMatcher)))),
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hasCondition(
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anyOf(binaryOperator(hasOperatorName("!="),
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hasLHS(IteratorComparisonMatcher),
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hasRHS(IteratorBoundMatcher)),
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binaryOperator(hasOperatorName("!="),
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hasLHS(IteratorBoundMatcher),
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hasRHS(IteratorComparisonMatcher)),
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OverloadedNEQMatcher)),
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hasIncrement(anyOf(
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unaryOperator(hasOperatorName("++"),
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hasUnaryOperand(declRefExpr(
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to(varDecl(hasType(pointsTo(AnyType)))
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.bind(IncrementVarName))))),
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cxxOperatorCallExpr(
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hasOverloadedOperatorName("++"),
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hasArgument(
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0, declRefExpr(to(varDecl(TestDerefReturnsByValue)
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.bind(IncrementVarName))))))))
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.bind(LoopNameIterator);
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}
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/// \brief The matcher used for array-like containers (pseudoarrays).
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///
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/// This matcher is more flexible than array-based loops. It will match
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/// loops of the following textual forms (regardless of whether the
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/// iterator type is actually a pointer type or a class type):
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///
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/// Assuming f, g, and h are of type containerType::iterator,
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/// \code
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/// for (int i = 0, j = container.size(); f < g; ++h) { ... }
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/// for (int i = 0; f < container.size(); ++h) { ... }
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/// \endcode
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/// The following string identifiers are bound to the parts of the AST:
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/// InitVarName: 'i' (as a VarDecl)
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/// ConditionVarName: 'f' (as a VarDecl)
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/// LoopName: The entire for loop (as a ForStmt)
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/// In the first example only:
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/// EndVarName: 'j' (as a VarDecl)
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/// ConditionEndVarName: 'g' (as a VarDecl)
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/// In the second example only:
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/// EndCallName: 'container.size()' (as a CXXMemberCallExpr)
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///
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/// Client code will need to make sure that:
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/// - The index variables 'i', 'f', and 'h' are the same.
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/// - The containers on which 'size()' is called is the container indexed.
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/// - The index variable is only used in overloaded operator[] or
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/// container.at().
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/// - If the end iterator variable 'g' is defined, it is the same as 'j'.
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/// - The container's iterators would not be invalidated during the loop.
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StatementMatcher makePseudoArrayLoopMatcher() {
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// Test that the incoming type has a record declaration that has methods
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// called 'begin' and 'end'. If the incoming type is const, then make sure
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// these methods are also marked const.
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//
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// FIXME: To be completely thorough this matcher should also ensure the
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// return type of begin/end is an iterator that dereferences to the same as
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// what operator[] or at() returns. Such a test isn't likely to fail except
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// for pathological cases.
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//
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// FIXME: Also, a record doesn't necessarily need begin() and end(). Free
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// functions called begin() and end() taking the container as an argument
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// are also allowed.
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TypeMatcher RecordWithBeginEnd = qualType(anyOf(
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qualType(isConstQualified(),
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hasDeclaration(cxxRecordDecl(
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hasMethod(cxxMethodDecl(hasName("begin"), isConst())),
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hasMethod(cxxMethodDecl(hasName("end"),
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isConst())))) // hasDeclaration
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), // qualType
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qualType(
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unless(isConstQualified()),
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hasDeclaration(cxxRecordDecl(hasMethod(hasName("begin")),
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hasMethod(hasName("end"))))) // qualType
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));
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StatementMatcher SizeCallMatcher = cxxMemberCallExpr(
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argumentCountIs(0),
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callee(cxxMethodDecl(anyOf(hasName("size"), hasName("length")))),
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on(anyOf(hasType(pointsTo(RecordWithBeginEnd)),
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hasType(RecordWithBeginEnd))));
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StatementMatcher EndInitMatcher =
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expr(anyOf(ignoringParenImpCasts(expr(SizeCallMatcher).bind(EndCallName)),
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explicitCastExpr(hasSourceExpression(ignoringParenImpCasts(
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expr(SizeCallMatcher).bind(EndCallName))))));
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DeclarationMatcher EndDeclMatcher =
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varDecl(hasInitializer(EndInitMatcher)).bind(EndVarName);
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StatementMatcher IndexBoundMatcher =
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expr(anyOf(ignoringParenImpCasts(declRefExpr(to(
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varDecl(hasType(isInteger())).bind(ConditionEndVarName)))),
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EndInitMatcher));
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return forStmt(
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unless(isInTemplateInstantiation()),
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hasLoopInit(
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anyOf(declStmt(declCountIs(2),
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containsDeclaration(0, InitToZeroMatcher),
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containsDeclaration(1, EndDeclMatcher)),
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declStmt(hasSingleDecl(InitToZeroMatcher)))),
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hasCondition(anyOf(
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binaryOperator(hasOperatorName("<"),
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hasLHS(IntegerComparisonMatcher),
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hasRHS(IndexBoundMatcher)),
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binaryOperator(hasOperatorName(">"), hasLHS(IndexBoundMatcher),
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hasRHS(IntegerComparisonMatcher)))),
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hasIncrement(unaryOperator(hasOperatorName("++"),
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hasUnaryOperand(IncrementVarMatcher))))
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.bind(LoopNamePseudoArray);
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}
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/// \brief Determine whether Init appears to be an initializing an iterator.
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///
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/// If it is, returns the object whose begin() or end() method is called, and
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/// the output parameter isArrow is set to indicate whether the initialization
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/// is called via . or ->.
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static const Expr *getContainerFromBeginEndCall(const Expr *Init, bool IsBegin,
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bool *IsArrow) {
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// FIXME: Maybe allow declaration/initialization outside of the for loop.
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const auto *TheCall =
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dyn_cast_or_null<CXXMemberCallExpr>(digThroughConstructors(Init));
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if (!TheCall || TheCall->getNumArgs() != 0)
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return nullptr;
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const auto *Member = dyn_cast<MemberExpr>(TheCall->getCallee());
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if (!Member)
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return nullptr;
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StringRef Name = Member->getMemberDecl()->getName();
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StringRef TargetName = IsBegin ? "begin" : "end";
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StringRef ConstTargetName = IsBegin ? "cbegin" : "cend";
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if (Name != TargetName && Name != ConstTargetName)
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return nullptr;
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const Expr *SourceExpr = Member->getBase();
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if (!SourceExpr)
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return nullptr;
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*IsArrow = Member->isArrow();
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return SourceExpr;
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}
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/// \brief Determines the container whose begin() and end() functions are called
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/// for an iterator-based loop.
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///
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/// BeginExpr must be a member call to a function named "begin()", and EndExpr
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/// must be a member.
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static const Expr *findContainer(ASTContext *Context, const Expr *BeginExpr,
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const Expr *EndExpr,
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bool *ContainerNeedsDereference) {
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// Now that we know the loop variable and test expression, make sure they are
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// valid.
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bool BeginIsArrow = false;
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bool EndIsArrow = false;
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const Expr *BeginContainerExpr =
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getContainerFromBeginEndCall(BeginExpr, /*IsBegin=*/true, &BeginIsArrow);
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if (!BeginContainerExpr)
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return nullptr;
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const Expr *EndContainerExpr =
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getContainerFromBeginEndCall(EndExpr, /*IsBegin=*/false, &EndIsArrow);
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// Disallow loops that try evil things like this (note the dot and arrow):
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// for (IteratorType It = Obj.begin(), E = Obj->end(); It != E; ++It) { }
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if (!EndContainerExpr || BeginIsArrow != EndIsArrow ||
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!areSameExpr(Context, EndContainerExpr, BeginContainerExpr))
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return nullptr;
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*ContainerNeedsDereference = BeginIsArrow;
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return BeginContainerExpr;
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}
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/// \brief Obtain the original source code text from a SourceRange.
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static StringRef getStringFromRange(SourceManager &SourceMgr,
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const LangOptions &LangOpts,
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SourceRange Range) {
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if (SourceMgr.getFileID(Range.getBegin()) !=
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SourceMgr.getFileID(Range.getEnd())) {
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return StringRef(); // Empty string.
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}
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return Lexer::getSourceText(CharSourceRange(Range, true), SourceMgr,
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LangOpts);
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}
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/// \brief If the given expression is actually a DeclRefExpr or a MemberExpr,
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/// find and return the underlying ValueDecl; otherwise, return NULL.
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static const ValueDecl *getReferencedVariable(const Expr *E) {
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if (const DeclRefExpr *DRE = getDeclRef(E))
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return dyn_cast<VarDecl>(DRE->getDecl());
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if (const auto *Mem = dyn_cast<MemberExpr>(E->IgnoreParenImpCasts()))
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return dyn_cast<FieldDecl>(Mem->getMemberDecl());
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return nullptr;
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}
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/// \brief Returns true when the given expression is a member expression
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/// whose base is `this` (implicitly or not).
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static bool isDirectMemberExpr(const Expr *E) {
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if (const auto *Member = dyn_cast<MemberExpr>(E->IgnoreParenImpCasts()))
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return isa<CXXThisExpr>(Member->getBase()->IgnoreParenImpCasts());
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return false;
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}
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/// \brief Given an expression that represents an usage of an element from the
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/// containter that we are iterating over, returns false when it can be
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/// guaranteed this element cannot be modified as a result of this usage.
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static bool canBeModified(ASTContext *Context, const Expr *E) {
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if (E->getType().isConstQualified())
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return false;
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auto Parents = Context->getParents(*E);
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if (Parents.size() != 1)
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return true;
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if (const auto *Cast = Parents[0].get<ImplicitCastExpr>()) {
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if ((Cast->getCastKind() == CK_NoOp &&
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Cast->getType() == E->getType().withConst()) ||
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(Cast->getCastKind() == CK_LValueToRValue &&
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!Cast->getType().isNull() && Cast->getType()->isFundamentalType()))
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return false;
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}
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// FIXME: Make this function more generic.
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return true;
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}
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/// \brief Returns true when it can be guaranteed that the elements of the
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/// container are not being modified.
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static bool usagesAreConst(ASTContext *Context, const UsageResult &Usages) {
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for (const Usage &U : Usages) {
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// Lambda captures are just redeclarations (VarDecl) of the same variable,
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// not expressions. If we want to know if a variable that is captured by
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// reference can be modified in an usage inside the lambda's body, we need
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// to find the expression corresponding to that particular usage, later in
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// this loop.
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if (U.Kind != Usage::UK_CaptureByCopy && U.Kind != Usage::UK_CaptureByRef &&
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canBeModified(Context, U.Expression))
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return false;
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}
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return true;
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}
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/// \brief Returns true if the elements of the container are never accessed
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/// by reference.
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static bool usagesReturnRValues(const UsageResult &Usages) {
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for (const auto &U : Usages) {
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if (U.Expression && !U.Expression->isRValue())
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return false;
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}
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return true;
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}
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/// \brief Returns true if the container is const-qualified.
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static bool containerIsConst(const Expr *ContainerExpr, bool Dereference) {
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if (const auto *VDec = getReferencedVariable(ContainerExpr)) {
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QualType CType = VDec->getType();
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if (Dereference) {
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if (!CType->isPointerType())
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return false;
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CType = CType->getPointeeType();
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}
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// If VDec is a reference to a container, Dereference is false,
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// but we still need to check the const-ness of the underlying container
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// type.
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CType = CType.getNonReferenceType();
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return CType.isConstQualified();
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}
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return false;
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}
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LoopConvertCheck::RangeDescriptor::RangeDescriptor()
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: ContainerNeedsDereference(false), DerefByConstRef(false),
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DerefByValue(false) {}
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LoopConvertCheck::LoopConvertCheck(StringRef Name, ClangTidyContext *Context)
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: ClangTidyCheck(Name, Context), TUInfo(new TUTrackingInfo),
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MaxCopySize(std::stoull(Options.get("MaxCopySize", "16"))),
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MinConfidence(StringSwitch<Confidence::Level>(
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Options.get("MinConfidence", "reasonable"))
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.Case("safe", Confidence::CL_Safe)
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.Case("risky", Confidence::CL_Risky)
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.Default(Confidence::CL_Reasonable)),
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NamingStyle(StringSwitch<VariableNamer::NamingStyle>(
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Options.get("NamingStyle", "CamelCase"))
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.Case("camelBack", VariableNamer::NS_CamelBack)
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.Case("lower_case", VariableNamer::NS_LowerCase)
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.Case("UPPER_CASE", VariableNamer::NS_UpperCase)
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.Default(VariableNamer::NS_CamelCase)) {}
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void LoopConvertCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
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Options.store(Opts, "MaxCopySize", std::to_string(MaxCopySize));
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SmallVector<std::string, 3> Confs{"risky", "reasonable", "safe"};
|
|
Options.store(Opts, "MinConfidence", Confs[static_cast<int>(MinConfidence)]);
|
|
|
|
SmallVector<std::string, 4> Styles{"camelBack", "CamelCase", "lower_case",
|
|
"UPPER_CASE"};
|
|
Options.store(Opts, "NamingStyle", Styles[static_cast<int>(NamingStyle)]);
|
|
}
|
|
|
|
void LoopConvertCheck::registerMatchers(MatchFinder *Finder) {
|
|
// Only register the matchers for C++. Because this checker is used for
|
|
// modernization, it is reasonable to run it on any C++ standard with the
|
|
// assumption the user is trying to modernize their codebase.
|
|
if (!getLangOpts().CPlusPlus)
|
|
return;
|
|
|
|
Finder->addMatcher(makeArrayLoopMatcher(), this);
|
|
Finder->addMatcher(makeIteratorLoopMatcher(), this);
|
|
Finder->addMatcher(makePseudoArrayLoopMatcher(), this);
|
|
}
|
|
|
|
/// \brief Given the range of a single declaration, such as:
|
|
/// \code
|
|
/// unsigned &ThisIsADeclarationThatCanSpanSeveralLinesOfCode =
|
|
/// InitializationValues[I];
|
|
/// next_instruction;
|
|
/// \endcode
|
|
/// Finds the range that has to be erased to remove this declaration without
|
|
/// leaving empty lines, by extending the range until the beginning of the
|
|
/// next instruction.
|
|
///
|
|
/// We need to delete a potential newline after the deleted alias, as
|
|
/// clang-format will leave empty lines untouched. For all other formatting we
|
|
/// rely on clang-format to fix it.
|
|
void LoopConvertCheck::getAliasRange(SourceManager &SM, SourceRange &Range) {
|
|
bool Invalid = false;
|
|
const char *TextAfter =
|
|
SM.getCharacterData(Range.getEnd().getLocWithOffset(1), &Invalid);
|
|
if (Invalid)
|
|
return;
|
|
unsigned Offset = std::strspn(TextAfter, " \t\r\n");
|
|
Range =
|
|
SourceRange(Range.getBegin(), Range.getEnd().getLocWithOffset(Offset));
|
|
}
|
|
|
|
/// \brief Computes the changes needed to convert a given for loop, and
|
|
/// applies them.
|
|
void LoopConvertCheck::doConversion(
|
|
ASTContext *Context, const VarDecl *IndexVar,
|
|
const ValueDecl *MaybeContainer, const UsageResult &Usages,
|
|
const DeclStmt *AliasDecl, bool AliasUseRequired, bool AliasFromForInit,
|
|
const ForStmt *Loop, RangeDescriptor Descriptor) {
|
|
auto Diag = diag(Loop->getForLoc(), "use range-based for loop instead");
|
|
|
|
std::string VarName;
|
|
bool VarNameFromAlias = (Usages.size() == 1) && AliasDecl;
|
|
bool AliasVarIsRef = false;
|
|
bool CanCopy = true;
|
|
|
|
if (VarNameFromAlias) {
|
|
const auto *AliasVar = cast<VarDecl>(AliasDecl->getSingleDecl());
|
|
VarName = AliasVar->getName().str();
|
|
AliasVarIsRef = AliasVar->getType()->isReferenceType();
|
|
|
|
// We keep along the entire DeclStmt to keep the correct range here.
|
|
SourceRange ReplaceRange = AliasDecl->getSourceRange();
|
|
|
|
std::string ReplacementText;
|
|
if (AliasUseRequired) {
|
|
ReplacementText = VarName;
|
|
} else if (AliasFromForInit) {
|
|
// FIXME: Clang includes the location of the ';' but only for DeclStmt's
|
|
// in a for loop's init clause. Need to put this ';' back while removing
|
|
// the declaration of the alias variable. This is probably a bug.
|
|
ReplacementText = ";";
|
|
} else {
|
|
// Avoid leaving empty lines or trailing whitespaces.
|
|
getAliasRange(Context->getSourceManager(), ReplaceRange);
|
|
}
|
|
|
|
Diag << FixItHint::CreateReplacement(
|
|
CharSourceRange::getTokenRange(ReplaceRange), ReplacementText);
|
|
// No further replacements are made to the loop, since the iterator or index
|
|
// was used exactly once - in the initialization of AliasVar.
|
|
} else {
|
|
VariableNamer Namer(&TUInfo->getGeneratedDecls(),
|
|
&TUInfo->getParentFinder().getStmtToParentStmtMap(),
|
|
Loop, IndexVar, MaybeContainer, Context, NamingStyle);
|
|
VarName = Namer.createIndexName();
|
|
// First, replace all usages of the array subscript expression with our new
|
|
// variable.
|
|
for (const auto &Usage : Usages) {
|
|
std::string ReplaceText;
|
|
SourceRange Range = Usage.Range;
|
|
if (Usage.Expression) {
|
|
// If this is an access to a member through the arrow operator, after
|
|
// the replacement it must be accessed through the '.' operator.
|
|
ReplaceText = Usage.Kind == Usage::UK_MemberThroughArrow ? VarName + "."
|
|
: VarName;
|
|
auto Parents = Context->getParents(*Usage.Expression);
|
|
if (Parents.size() == 1) {
|
|
if (const auto *Paren = Parents[0].get<ParenExpr>()) {
|
|
// Usage.Expression will be replaced with the new index variable,
|
|
// and parenthesis around a simple DeclRefExpr can always be
|
|
// removed.
|
|
Range = Paren->getSourceRange();
|
|
} else if (const auto *UOP = Parents[0].get<UnaryOperator>()) {
|
|
// If we are taking the address of the loop variable, then we must
|
|
// not use a copy, as it would mean taking the address of the loop's
|
|
// local index instead.
|
|
// FIXME: This won't catch cases where the address is taken outside
|
|
// of the loop's body (for instance, in a function that got the
|
|
// loop's index as a const reference parameter), or where we take
|
|
// the address of a member (like "&Arr[i].A.B.C").
|
|
if (UOP->getOpcode() == UO_AddrOf)
|
|
CanCopy = false;
|
|
}
|
|
}
|
|
} else {
|
|
// The Usage expression is only null in case of lambda captures (which
|
|
// are VarDecl). If the index is captured by value, add '&' to capture
|
|
// by reference instead.
|
|
ReplaceText =
|
|
Usage.Kind == Usage::UK_CaptureByCopy ? "&" + VarName : VarName;
|
|
}
|
|
TUInfo->getReplacedVars().insert(std::make_pair(Loop, IndexVar));
|
|
Diag << FixItHint::CreateReplacement(
|
|
CharSourceRange::getTokenRange(Range), ReplaceText);
|
|
}
|
|
}
|
|
|
|
// Now, we need to construct the new range expression.
|
|
SourceRange ParenRange(Loop->getLParenLoc(), Loop->getRParenLoc());
|
|
|
|
QualType Type = Context->getAutoDeductType();
|
|
if (!Descriptor.ElemType.isNull() && Descriptor.ElemType->isFundamentalType())
|
|
Type = Descriptor.ElemType.getUnqualifiedType();
|
|
|
|
// If the new variable name is from the aliased variable, then the reference
|
|
// type for the new variable should only be used if the aliased variable was
|
|
// declared as a reference.
|
|
bool IsCheapToCopy =
|
|
!Descriptor.ElemType.isNull() &&
|
|
Descriptor.ElemType.isTriviallyCopyableType(*Context) &&
|
|
// TypeInfo::Width is in bits.
|
|
Context->getTypeInfo(Descriptor.ElemType).Width <= 8 * MaxCopySize;
|
|
bool UseCopy = CanCopy && ((VarNameFromAlias && !AliasVarIsRef) ||
|
|
(Descriptor.DerefByConstRef && IsCheapToCopy));
|
|
|
|
if (!UseCopy) {
|
|
if (Descriptor.DerefByConstRef) {
|
|
Type = Context->getLValueReferenceType(Context->getConstType(Type));
|
|
} else if (Descriptor.DerefByValue) {
|
|
if (!IsCheapToCopy)
|
|
Type = Context->getRValueReferenceType(Type);
|
|
} else {
|
|
Type = Context->getLValueReferenceType(Type);
|
|
}
|
|
}
|
|
|
|
StringRef MaybeDereference = Descriptor.ContainerNeedsDereference ? "*" : "";
|
|
std::string TypeString = Type.getAsString(getLangOpts());
|
|
std::string Range = ("(" + TypeString + " " + VarName + " : " +
|
|
MaybeDereference + Descriptor.ContainerString + ")")
|
|
.str();
|
|
Diag << FixItHint::CreateReplacement(
|
|
CharSourceRange::getTokenRange(ParenRange), Range);
|
|
TUInfo->getGeneratedDecls().insert(make_pair(Loop, VarName));
|
|
}
|
|
|
|
/// \brief Returns a string which refers to the container iterated over.
|
|
StringRef LoopConvertCheck::getContainerString(ASTContext *Context,
|
|
const ForStmt *Loop,
|
|
const Expr *ContainerExpr) {
|
|
StringRef ContainerString;
|
|
if (isa<CXXThisExpr>(ContainerExpr->IgnoreParenImpCasts())) {
|
|
ContainerString = "this";
|
|
} else {
|
|
ContainerString =
|
|
getStringFromRange(Context->getSourceManager(), Context->getLangOpts(),
|
|
ContainerExpr->getSourceRange());
|
|
}
|
|
|
|
return ContainerString;
|
|
}
|
|
|
|
/// \brief Determines what kind of 'auto' must be used after converting a for
|
|
/// loop that iterates over an array or pseudoarray.
|
|
void LoopConvertCheck::getArrayLoopQualifiers(ASTContext *Context,
|
|
const BoundNodes &Nodes,
|
|
const Expr *ContainerExpr,
|
|
const UsageResult &Usages,
|
|
RangeDescriptor &Descriptor) {
|
|
// On arrays and pseudoarrays, we must figure out the qualifiers from the
|
|
// usages.
|
|
if (usagesAreConst(Context, Usages) ||
|
|
containerIsConst(ContainerExpr, Descriptor.ContainerNeedsDereference)) {
|
|
Descriptor.DerefByConstRef = true;
|
|
}
|
|
if (usagesReturnRValues(Usages)) {
|
|
// If the index usages (dereference, subscript, at, ...) return rvalues,
|
|
// then we should not use a reference, because we need to keep the code
|
|
// correct if it mutates the returned objects.
|
|
Descriptor.DerefByValue = true;
|
|
}
|
|
// Try to find the type of the elements on the container, to check if
|
|
// they are trivially copyable.
|
|
for (const Usage &U : Usages) {
|
|
if (!U.Expression || U.Expression->getType().isNull())
|
|
continue;
|
|
QualType Type = U.Expression->getType().getCanonicalType();
|
|
if (U.Kind == Usage::UK_MemberThroughArrow) {
|
|
if (!Type->isPointerType()) {
|
|
continue;
|
|
}
|
|
Type = Type->getPointeeType();
|
|
}
|
|
Descriptor.ElemType = Type;
|
|
}
|
|
}
|
|
|
|
/// \brief Determines what kind of 'auto' must be used after converting an
|
|
/// iterator based for loop.
|
|
void LoopConvertCheck::getIteratorLoopQualifiers(ASTContext *Context,
|
|
const BoundNodes &Nodes,
|
|
RangeDescriptor &Descriptor) {
|
|
// The matchers for iterator loops provide bound nodes to obtain this
|
|
// information.
|
|
const auto *InitVar = Nodes.getDeclAs<VarDecl>(InitVarName);
|
|
QualType CanonicalInitVarType = InitVar->getType().getCanonicalType();
|
|
const auto *DerefByValueType =
|
|
Nodes.getNodeAs<QualType>(DerefByValueResultName);
|
|
Descriptor.DerefByValue = DerefByValueType;
|
|
|
|
if (Descriptor.DerefByValue) {
|
|
// If the dereference operator returns by value then test for the
|
|
// canonical const qualification of the init variable type.
|
|
Descriptor.DerefByConstRef = CanonicalInitVarType.isConstQualified();
|
|
Descriptor.ElemType = *DerefByValueType;
|
|
} else {
|
|
if (const auto *DerefType =
|
|
Nodes.getNodeAs<QualType>(DerefByRefResultName)) {
|
|
// A node will only be bound with DerefByRefResultName if we're dealing
|
|
// with a user-defined iterator type. Test the const qualification of
|
|
// the reference type.
|
|
auto ValueType = DerefType->getNonReferenceType();
|
|
|
|
Descriptor.DerefByConstRef = ValueType.isConstQualified();
|
|
Descriptor.ElemType = ValueType;
|
|
} else {
|
|
// By nature of the matcher this case is triggered only for built-in
|
|
// iterator types (i.e. pointers).
|
|
assert(isa<PointerType>(CanonicalInitVarType) &&
|
|
"Non-class iterator type is not a pointer type");
|
|
|
|
// We test for const qualification of the pointed-at type.
|
|
Descriptor.DerefByConstRef =
|
|
CanonicalInitVarType->getPointeeType().isConstQualified();
|
|
Descriptor.ElemType = CanonicalInitVarType->getPointeeType();
|
|
}
|
|
}
|
|
}
|
|
|
|
/// \brief Determines the parameters needed to build the range replacement.
|
|
void LoopConvertCheck::determineRangeDescriptor(
|
|
ASTContext *Context, const BoundNodes &Nodes, const ForStmt *Loop,
|
|
LoopFixerKind FixerKind, const Expr *ContainerExpr,
|
|
const UsageResult &Usages, RangeDescriptor &Descriptor) {
|
|
Descriptor.ContainerString = getContainerString(Context, Loop, ContainerExpr);
|
|
|
|
if (FixerKind == LFK_Iterator)
|
|
getIteratorLoopQualifiers(Context, Nodes, Descriptor);
|
|
else
|
|
getArrayLoopQualifiers(Context, Nodes, ContainerExpr, Usages, Descriptor);
|
|
}
|
|
|
|
/// \brief Check some of the conditions that must be met for the loop to be
|
|
/// convertible.
|
|
bool LoopConvertCheck::isConvertible(ASTContext *Context,
|
|
const ast_matchers::BoundNodes &Nodes,
|
|
const ForStmt *Loop,
|
|
LoopFixerKind FixerKind) {
|
|
// If we already modified the range of this for loop, don't do any further
|
|
// updates on this iteration.
|
|
if (TUInfo->getReplacedVars().count(Loop))
|
|
return false;
|
|
|
|
// Check that we have exactly one index variable and at most one end variable.
|
|
const auto *LoopVar = Nodes.getDeclAs<VarDecl>(IncrementVarName);
|
|
const auto *CondVar = Nodes.getDeclAs<VarDecl>(ConditionVarName);
|
|
const auto *InitVar = Nodes.getDeclAs<VarDecl>(InitVarName);
|
|
if (!areSameVariable(LoopVar, CondVar) || !areSameVariable(LoopVar, InitVar))
|
|
return false;
|
|
const auto *EndVar = Nodes.getDeclAs<VarDecl>(EndVarName);
|
|
const auto *ConditionEndVar = Nodes.getDeclAs<VarDecl>(ConditionEndVarName);
|
|
if (EndVar && !areSameVariable(EndVar, ConditionEndVar))
|
|
return false;
|
|
|
|
// FIXME: Try to put most of this logic inside a matcher.
|
|
if (FixerKind == LFK_Iterator) {
|
|
QualType InitVarType = InitVar->getType();
|
|
QualType CanonicalInitVarType = InitVarType.getCanonicalType();
|
|
|
|
const auto *BeginCall = Nodes.getNodeAs<CXXMemberCallExpr>(BeginCallName);
|
|
assert(BeginCall && "Bad Callback. No begin call expression");
|
|
QualType CanonicalBeginType =
|
|
BeginCall->getMethodDecl()->getReturnType().getCanonicalType();
|
|
if (CanonicalBeginType->isPointerType() &&
|
|
CanonicalInitVarType->isPointerType()) {
|
|
// If the initializer and the variable are both pointers check if the
|
|
// un-qualified pointee types match, otherwise we don't use auto.
|
|
if (!Context->hasSameUnqualifiedType(
|
|
CanonicalBeginType->getPointeeType(),
|
|
CanonicalInitVarType->getPointeeType()))
|
|
return false;
|
|
} else if (!Context->hasSameType(CanonicalInitVarType,
|
|
CanonicalBeginType)) {
|
|
// Check for qualified types to avoid conversions from non-const to const
|
|
// iterator types.
|
|
return false;
|
|
}
|
|
} else if (FixerKind == LFK_PseudoArray) {
|
|
// This call is required to obtain the container.
|
|
const auto *EndCall = Nodes.getStmtAs<CXXMemberCallExpr>(EndCallName);
|
|
if (!EndCall || !dyn_cast<MemberExpr>(EndCall->getCallee()))
|
|
return false;
|
|
}
|
|
return true;
|
|
}
|
|
|
|
void LoopConvertCheck::check(const MatchFinder::MatchResult &Result) {
|
|
const BoundNodes &Nodes = Result.Nodes;
|
|
Confidence ConfidenceLevel(Confidence::CL_Safe);
|
|
ASTContext *Context = Result.Context;
|
|
|
|
const ForStmt *Loop;
|
|
LoopFixerKind FixerKind;
|
|
RangeDescriptor Descriptor;
|
|
|
|
if ((Loop = Nodes.getStmtAs<ForStmt>(LoopNameArray))) {
|
|
FixerKind = LFK_Array;
|
|
} else if ((Loop = Nodes.getStmtAs<ForStmt>(LoopNameIterator))) {
|
|
FixerKind = LFK_Iterator;
|
|
} else {
|
|
Loop = Nodes.getStmtAs<ForStmt>(LoopNamePseudoArray);
|
|
assert(Loop && "Bad Callback. No for statement");
|
|
FixerKind = LFK_PseudoArray;
|
|
}
|
|
|
|
if (!isConvertible(Context, Nodes, Loop, FixerKind))
|
|
return;
|
|
|
|
const auto *LoopVar = Nodes.getDeclAs<VarDecl>(IncrementVarName);
|
|
const auto *EndVar = Nodes.getDeclAs<VarDecl>(EndVarName);
|
|
|
|
// If the loop calls end()/size() after each iteration, lower our confidence
|
|
// level.
|
|
if (FixerKind != LFK_Array && !EndVar)
|
|
ConfidenceLevel.lowerTo(Confidence::CL_Reasonable);
|
|
|
|
// If the end comparison isn't a variable, we can try to work with the
|
|
// expression the loop variable is being tested against instead.
|
|
const auto *EndCall = Nodes.getStmtAs<CXXMemberCallExpr>(EndCallName);
|
|
const auto *BoundExpr = Nodes.getStmtAs<Expr>(ConditionBoundName);
|
|
|
|
// Find container expression of iterators and pseudoarrays, and determine if
|
|
// this expression needs to be dereferenced to obtain the container.
|
|
// With array loops, the container is often discovered during the
|
|
// ForLoopIndexUseVisitor traversal.
|
|
const Expr *ContainerExpr = nullptr;
|
|
if (FixerKind == LFK_Iterator) {
|
|
ContainerExpr = findContainer(Context, LoopVar->getInit(),
|
|
EndVar ? EndVar->getInit() : EndCall,
|
|
&Descriptor.ContainerNeedsDereference);
|
|
} else if (FixerKind == LFK_PseudoArray) {
|
|
ContainerExpr = EndCall->getImplicitObjectArgument();
|
|
Descriptor.ContainerNeedsDereference =
|
|
dyn_cast<MemberExpr>(EndCall->getCallee())->isArrow();
|
|
}
|
|
|
|
// We must know the container or an array length bound.
|
|
if (!ContainerExpr && !BoundExpr)
|
|
return;
|
|
|
|
ForLoopIndexUseVisitor Finder(Context, LoopVar, EndVar, ContainerExpr,
|
|
BoundExpr,
|
|
Descriptor.ContainerNeedsDereference);
|
|
|
|
// Find expressions and variables on which the container depends.
|
|
if (ContainerExpr) {
|
|
ComponentFinderASTVisitor ComponentFinder;
|
|
ComponentFinder.findExprComponents(ContainerExpr->IgnoreParenImpCasts());
|
|
Finder.addComponents(ComponentFinder.getComponents());
|
|
}
|
|
|
|
// Find usages of the loop index. If they are not used in a convertible way,
|
|
// stop here.
|
|
if (!Finder.findAndVerifyUsages(Loop->getBody()))
|
|
return;
|
|
ConfidenceLevel.lowerTo(Finder.getConfidenceLevel());
|
|
|
|
// Obtain the container expression, if we don't have it yet.
|
|
if (FixerKind == LFK_Array) {
|
|
ContainerExpr = Finder.getContainerIndexed()->IgnoreParenImpCasts();
|
|
|
|
// Very few loops are over expressions that generate arrays rather than
|
|
// array variables. Consider loops over arrays that aren't just represented
|
|
// by a variable to be risky conversions.
|
|
if (!getReferencedVariable(ContainerExpr) &&
|
|
!isDirectMemberExpr(ContainerExpr))
|
|
ConfidenceLevel.lowerTo(Confidence::CL_Risky);
|
|
}
|
|
|
|
// Find out which qualifiers we have to use in the loop range.
|
|
const UsageResult &Usages = Finder.getUsages();
|
|
determineRangeDescriptor(Context, Nodes, Loop, FixerKind, ContainerExpr,
|
|
Usages, Descriptor);
|
|
|
|
// Ensure that we do not try to move an expression dependent on a local
|
|
// variable declared inside the loop outside of it.
|
|
// FIXME: Determine when the external dependency isn't an expression converted
|
|
// by another loop.
|
|
TUInfo->getParentFinder().gatherAncestors(Context->getTranslationUnitDecl());
|
|
DependencyFinderASTVisitor DependencyFinder(
|
|
&TUInfo->getParentFinder().getStmtToParentStmtMap(),
|
|
&TUInfo->getParentFinder().getDeclToParentStmtMap(),
|
|
&TUInfo->getReplacedVars(), Loop);
|
|
|
|
if (DependencyFinder.dependsOnInsideVariable(ContainerExpr) ||
|
|
Descriptor.ContainerString.empty() || Usages.empty() ||
|
|
ConfidenceLevel.getLevel() < MinConfidence)
|
|
return;
|
|
|
|
doConversion(Context, LoopVar, getReferencedVariable(ContainerExpr), Usages,
|
|
Finder.getAliasDecl(), Finder.aliasUseRequired(),
|
|
Finder.aliasFromForInit(), Loop, Descriptor);
|
|
}
|
|
|
|
} // namespace modernize
|
|
} // namespace tidy
|
|
} // namespace clang
|